Recorded data deleting device for hard disk

ABSTRACT

A recorded data eraser  1  defines therein a cavity  2  for insertion of a hard disk drive  20  in the cavity  2  and includes a coil  4  being arranged around the cavity  2  so as to encircle the hard disk drive  20  when the hard disk drive  20  is inserted in the cavity  2 , and a DC power supply circuit  8  for producing a magnetic field in the coil  4.

TECHNICAL FIELD

The present invention relates to a recorded data eraser for a hard diskdrive used for erasing data recorded in a hard disk drive.

BACKGROUND ART

When a hard disk drive is abandoned or reused, data recorded on a harddisk as a recording medium in the hard disk drive are commonly erased inview of confidential nature.

Such erase of recorded data in a hard disk drive is conventionally doneby repeatedly writing predetermined data such as “00” over data on thehard disk. However, the erasing process by the data overwriting has aproblem of heavy workloads and time-consuming. For example, it takesmore than 12 hours to erase data on a hard disk of 20 gigabytes ofstorage capacity.

On the other hand, as an eraser for erasing data on floppy disks andtapes, which are also recording media, a toroidal coil formed by aconductive wire wound around an outer periphery of a ring-shaped core,arranged in a casing of an eraser body and connected to an AC power isknown. The eraser arranges a floppy disk or a tape at an outer face ofthe eraser body and applies an alternating current to the coil from theAC power so as to generate an alternating magnetic field, wherebyerasing data recorded on the floppy disk or the tape.

However, in the case of erasing data in a hard disk drive by using theeraser, since a hard disk inside the hard disk drive is accommodatedwithin a casing made of metal such as iron and aluminum, the magneticforce does not reach the hard disk inside the hard disk drive, failingto erase data recorded on the hard disk only with the hard disk drivearranged at an outer face of the eraser and with a magnetic fieldgenerated by the eraser. To generate a stronger magnetic field, there isa problem to make a coil heavier, resulting in increasing a weight ofthe entire eraser.

It is therefore an object of the present invention made in view of theproblems and drawbacks described above to provide an advanced recordeddata eraser for a hard disk drive that erases data recorded on a harddisk readily and with certainty.

SUMMARY OF THE INVENTION

One embodiment of the present invention is a recorded data eraser for ahard disk drive defining therein a cavity for insertion of the hard diskdrive in the cavity and including a coil being arranged around thecavity so as to encircle the hard disk drive when the hard disk drive isinserted in the cavity, and a DC power supply circuit for producing (orgenerating) a magnetic field in the coil.

Since the eraser has the coil for production of the magnetic fieldarranged around the cavity so as to encircle the hard disk drive, thestrong magnetism produced in the coil is used for erasing data, therebyerasing data on a hard disk not only with the disk in the drive exposedbut also with the disk clad in a metal casing.

Further, the magnetic field produced in the coil is used effectively, soas to make the coil smaller and lighter in weight and thus making theentire eraser lighter in weight, compared with a conventionalarrangement of the hard disk drive at the outer side of the coil.

Another embodiment of the present invention is a recorded data eraserfor a hard disk drive defining therein a cavity for insertion of thehard disk drive in the cavity and including a coil being arranged aroundthe cavity so as to encircle the hard disk drive when the hard diskdrive is inserted in the cavity, a DC power supply circuit for producinga magnetic field in the coil, and a permanent magnet provided in aposition where the magnet exerts a magnetic force on the hard disk driveinserted in the cavity, adapted to maintain a magnetic flux density inthe cavity within the range of 6,000 to 15,000 gauss in erasing data inthe hard disk drive, wherein the DC power supply circuit includes acapacitor for charging and discharging and a switching device fordischarging the capacitor into the coil, and adapted to produce amagnetic field in the coil by the discharge of the capacitor forduration of 10 ms or less.

In addition to the first advantage, the permanent magnet is provided ina position where the magnet exerts a magnetic force on the hard diskdrive inserted in the cavity of the eraser, thereby ensuring furtherlightness in its weight. Further, the magnetic field produced in thecavity is set within the range of 6,000 to 15,000 gauss at the magneticflux density, thereby making sure to erase data. Still further, sincethe DC power supply circuit includes a capacitor for charging anddischarging and a switching device for discharging the capacitor intothe coil, the discharge of the capacitor into the coil by the switchingdevice produces the magnetic field in the coil. Yet further, productionof the magnetic field in the coil by the discharge of the capacitor isset for duration of 10 ms or less, thereby enabling an efficient dataerase in a short period.

Other objects, features, and advantages of the present invention willbecome more apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a data eraser that is an embodiment ofthe present invention;

FIG. 2 is a perspective view of a casing assembly incorporated in thedata eraser for arranging a coil as shown disassembled to itscomponents;

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1;

FIG. 4 is a circuit diagram of a DC power supply circuit built in thedata eraser of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 4 show a data eraser for a hard disk drive that is apreferred embodiment of the present invention.

Referring to the figures, a reference numeral 1 denotes the data eraserthat includes a cavity 2 for insertion of a hard disk drive, with anopening at one end face of the eraser, in an oval (a racetrack) shape atcross section, and extending horizontally.

A casing assembly 3 of a box shape for arranging a coil shown in FIG. 2is incorporated in the eraser 1. The casing assembly 3 consistsessentially of a first casing component 31 made of plastic and a secondcasing component 32 also made of plastic. The first casing component 31includes a rectangular flange 312 having an opening 311 of an oval (aracetrack) shape and a coil holder 313 of a tubular shape extendingbackward of the flange 312 from the edge of the opening 311 of theflange 312. The opening 311 and the internal space of the coil holder312 form the cavity 2 for insertion of the hard disk drive.

A conductive wire is wound around the coil holder 313 forming amultiplicity of loops toward a longitudinal direction of the coil holder313 along its outer periphery, thereby forming a coil 4.

The second casing component 32 in the casing assembly 3 is of arectangular cylinder with one open end. A shape of an opening 321 isalmost in conformity with that of the flange 312 of the first casingcomponent 31. A plurality of permanent magnets 5 are embedded in aninner surface of an upper part of the second casing component 321 withthe upper parts of the magnets 5 at a slightly inner portion of theupper wall.

The coil 4 formed around the coil holder 313 of the first casingcomponent 31 produces a magnetic field within the internal space of thecoil 4 (viz. the internal space of the coil holder 313) by beingenergized, by which magnetic field, data on the hard disk is erased, asdescribed below.

The permanent magnets 5 secured to the second casing component 32 applya magnetic field produced thereby to the magnetic field produced by thecoil 4, thereby applying a stronger magnetic field for erasing data tothe hard disk drive. In other words, the permanent magnets 5 are for anauxiliary for erasing data by the magnetic field in the coil 4.

Therefrom, the casing assembly 3 for arranging a coil is formed byassembling the first and second casing components 31 and 32 with thecoil holder 313 of the first casing component 31 being accommodatedinside the second casing component 32 from its opening 321, and with theflange 312 of the first casing component 31 being engaged with theopening 321.

As seen in FIG. 3, the outer periphery of the casing assembly 3 exceptthe opening 311 of flange of the first casing component 31 is clad in amagnetic-shielding plate 6 made of nonmagnetic material such asaluminum, so that magnetism by both the coil 4 and the permanent magnets5 is prevented from leaking out of the eraser as much as possible.Further, the outer periphery of the magnetic-shielding plate 6 is cladin plastic outer covering 7.

Electric power is supplied to the coil 4 from a DC power supply circuit8 shown in FIG. 4 and incorporated in the eraser. The reference numeral9 denotes a plug to connect the DC power supply circuit 8 with acommercial AC power source and the reference numeral 10 denotes a wiringcord pulled out from the data eraser 1.

The DC power supply circuit 8 shown in FIG. 4 includes a direct current(DC) converter 81 for converting a commercial alternating currentapplied via the plug 9 into a direct current of a predetermined powervoltage, a capacitor 82 charged by an electric power supply from the DCconverter 81 and connected in parallel with the coil 4, an reactor 83connected in an input line from the DC converter 81 to the capacitor 82,and a switching device 84 connected between the capacitor 82 and thecoil 4. Closing the switching device 84 discharges the capacitor 82 tothe coil 4, and by the discharge, the coil 4 produces the magnetic fieldtherein. Next, a method for using the data eraser 1 shown in FIGS. 1 to4 will be described in detail below.

With the switching device 84 of the DC power supply circuit 8 open,after the plug 9 of the eraser 1 is connected to the commercial powersource, as seen in FIGS. 1 and 2, a hard disk drive 20 whose data is tobe erased is inserted into the cavity 2 of the eraser 1 without exposinga hard disk therein, with the disk clad in a metal casing, and with thedepth direction adjusted hightwise. The capacitor 82 of the DC powersupply circuit 8 is charged by an electric power supply from the directcurrent converter 81.

In this state, closing the switching device 84 discharges the capacitor82 to the coil 4 and the discharge produces a magnetic field in theinternal space of the coil 4, that is, the cavity 2 where the hard diskdrive 20 is inserted. On the other hand, a magnetic field by thepermanent magnets 5 secured above the coil 4 also exerts on the cavity2, so that both of the magnetic fields by the coil 4 and the magnets 5exert on the hard disk drive 20.

Magnetism by these magnetic fields penetrates the metal casing made ofsuch as aluminum and iron of the hard disk drive 20 to exert on the harddisk therewithin, thereby erasing data recorded on the hard diskincluding cylinder information. After duration of a predetermined time,closing the switching device 84 stops producing the magnetic field bythe coil 4 so as to prepare for another data erase.

It is required to exert a stronger magnetism than a written magnetism onthe hard disk drive 20 for erasing written data including cylinderinformation. From this view, the stronger the magnetism by the coil 4and the permanent magnets 5 which exerts on the cavity 2 is the better.

However, the hard disk drive 20 incorporates a controlling portion forcontrolling the drive besides the hard disk of a disc shape for writingdata, so that too much enlargement of the magnetic field for dataerasing not only erases data but also destroys the controlling portion,resulting in a difficulty of a reuse of the drive 20.

Consequently, a size of the magnetic field acting on the drive 20 ispreferably set within the range of 6,000 to 15,000 gauss at a magneticflux density. The magnetic flux density less than 6,000 is inadequate toerase data. On the other hand, the magnetic flux density more then15,000 destroys not only data but also the controlling portion. Morepreferably, it is within the range of 8,000 to 13,000 gauss.

Herein, an intensity of the magnetic field by the coil 4 is adjustabledepending on change of the number of winding of the coil and a currentapplied to the coil.

Insertion of the hard disk drive 20 into the coil 4 in which the strongmagnetic field is produced obtains a large data erase effects with alittle weight of the coil. That is, the entire weight of the eraser 1can be made lighter. However, a combination of the coil 4 and thepermanent magnets 5, as the preferred embodiment, can provide furtherlighter in weight than a use of the coil 4 alone to obtain the magneticflux density within the range of 6,000 to 15,000 gauss without themagnets 5. More specifically, obtaining the magnetic flux density withinthe range of 6,000 to 15,000 gauss with the magnets 5 alone requires theentire weight exceeding 40 kg, compared with 4 kg with the coil 4 alone,and the eraser 1 can be provided lighter in weight and portable.

Further, a combination of the coil 4 and the magnets 5 makes its weightabout 2 kg, a half weight of the case described above. In this case, itis needless to say that the eraser 1 can be portable.

Duration for which the magnetic field is produced in the coil 4, inother words, for which that the switching device 84 is closed, is notlimited particularly, but preferably set for 10 ms or less. Even if theduration exceeds 10 ms, it achieves the same effect of data erase, orrather lowers energy efficiency and wastes time.

The hard disk drive 20 whose data is erased as described above isejected from the cavity 2 of the eraser 1, and abandoned or reused,depending on need.

Since the preferred embodiment has a coil for production of a magneticfield arranged around a cavity so as to encircle a hard disk drive, astrong magnetism produced in the coil is used for erasing data, therebyerasing data on a hard disk not only with the disk in the drive exposedbut also with the disk clad in a metal casing.

Further, the magnetic field produced in the coil is used effectively, soas to make the coil smaller and lighter in weight and thus making theentire eraser lighter in weight, compared with a conventionalarrangement of a hard disk drive at the outer side of the coil.

Further, in the case of a permanent magnet provided in a position wherethe magnet exerts a magnetic force on the hard disk drive inserted inthe cavity, it ensures further lightness in its weight.

Still further, in the case of the magnetic field produced in the cavityset within the range of 6,000 to 15,000 gauss at the magnetic fluxdensity, it makes sure to erase data.

In the case of the DC power supply circuit including a capacitor forcharging and discharging and a switching device for discharging thecapacitor into the coil, discharging the capacitor into the coil by theswitching device produces the magnetic field in the coil.

In this case, setting production of the magnetic field in the coil bythe discharge of the capacitor for duration of 10 ms or less enables anefficient data erase in a short period.

Hereinbefore, having described specific embodiments of the presentinvention in detail, the invention in not limited thereto, and variouschanges and modifications may be made in the invention without departingfrom the spirit and scope thereof.

INDUSTRIAL APPLICABILITY

The present invention is applicable as an eraser of data recorded on ahard disk drive.

1. A recorded data eraser for a hard disk drive defining therein a cavity for insertion of the hard disk drive in the cavity and comprising: a coil being arranged around the cavity so as to encircle the hard disk drive when the hard disk drive is inserted in the cavity; and a DC power supply circuit for producing a magnetic field in the coil.
 2. The recorded data eraser as defined in claim 1, further comprising a permanent magnet provided in a position where the magnet exerts a magnetic force on the hard disk drive inserted in the cavity.
 3. The recorded data eraser as defined in claim 1, wherein the hard disk drive is insertable in the cavity with the drive clad in a metal casing.
 4. The recorded data eraser as defined in claim 2, wherein the hard disk drive is insertable in the cavity with the drive clad in a metal casing.
 5. The recorded data eraser as defined in claim 1, adapted to maintain a magnetic flux density in the cavity within the range of 6,000 to 15,000 gauss in erasing data in the hard disk drive.
 6. The recorded data eraser as defined in claim 2, adapted to maintain a magnetic flux density in the cavity within the range of 6,000 to 15,000 gauss in erasing data in the hard disk drive.
 7. The recorded data eraser as defined in claim 1, adapted to maintain a magnetic flux density in the cavity within the range of 8,000 to 13,000 gauss in erasing data in the hard disk drive.
 8. The recorded data eraser as defined in claim 2, adapted to maintain a magnetic flux density in the cavity within the range of 8,000 to 13,000 gauss in erasing data in the hard disk drive.
 9. The recorded data eraser for as defined in claim 1, wherein the DC power supply circuit comprises a capacitor for charging and discharging and a switching device for discharging the capacitor into the coil.
 10. The recorded data eraser as defined in claim 2, wherein the DC power supply circuit comprises a capacitor for charging and discharging and a switching device for discharging the capacitor into the coil.
 11. The recorded data eraser as defined in claim 5, wherein the DC power supply circuit comprises a capacitor for charging and discharging and a switching device for discharging the capacitor into the coil.
 12. The recorded data eraser as defined in claim 6, wherein the DC power supply circuit comprises a capacitor for charging and discharging and a switching device for discharging the capacitor into the coil.
 13. The recorded data eraser as defined in claim 9, adapted to produce a magnetic field in the coil by the discharge of the capacitor for duration of 10 ms or less.
 14. The recorded data eraser as defined in claim 10, adapted to produce a magnetic field in the coil by the discharge of the capacitor for duration of 10 ms or less.
 15. The recorded data eraser as defined in claim 11, adapted to produce a magnetic field in the coil by the discharge of the capacitor for duration of 10 ms or less.
 16. The recorded data eraser as defined in claim 12, adapted to produce a magnetic field in the coil by the discharge of the capacitor for duration of 10 ms or less.
 17. A recorded data eraser for a hard disk drive defining therein a cavity for insertion of the hard disk drive in the cavity and comprising: a coil being arranged around the cavity so as to encircle the hard disk drive when the hard disk drive is inserted in the cavity; a DC power supply circuit for producing a magnetic field in the coil; and a permanent magnet provided in a position where the magnet exerts a magnetic force on the hard disk drive inserted in the cavity; adapted to maintain a magnetic flux density in the cavity within the range of 6,000 to 15,000 gauss in erasing data in the hard disk drive, wherein the DC power supply circuit comprises a capacitor for charging and discharging and a switching device for discharging the capacitor into the coil, and adapted to produce a magnetic field in the coil by the discharge of the capacitor for duration of 10 ms or less.
 18. The recorded data eraser as defined in claim 17, wherein the permanent magnet is provided in a position where the magnet exerts a magnetic force on the hard disk drive inserted in the cavity. 